EP3431866B1 - Dual function light module - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to the field of headlights for motor vehicles which can provide, for example, the functions of high beam and/or dipped beam and/or fog lights. The invention relates in particular to dual-function light modules, integrated into these headlights, and making it possible to provide at least two of the functions mentioned.

BACKGROUND

The projection of a light beam by a motor vehicle headlight is traditionally used to illuminate the road and thus increase visibility in the dark, for example at night. This allows the vehicle to be driven safely.

Headlights usually perform the functions of dipped beam, main beam or fog lights. Dipped beam headlights are distinguished from other lights because they have a cut-off to avoid dazzling other road users, particularly those coming towards the vehicle. This cut-off, which takes the form of a "cut-off line", creates a transition zone between a lit area and a dark area. The shape of the cut-off line is generally subject to regulations, for example regulation R123 ECE or R112 ECE.

High beams are "full" beams with no dark area. Thus, there are dual-function light modules, allowing a dipped beam function and one of the high beam or fog light functions. Such a dual-function module includes a folder, allowing a cut-off line to be formed that complies with regulatory constraints. The cut-off line is created by the folder positioned in front of a light source so that the beam cut-off line is an image of the edge of the folder formed by the projection lens.

Such a dual-function light module comprising a folder is for example described in the patent applications WO2013-120121 A1 , FROM 10 2012 203 929 B3 , FROM 10 2016 122 860 A1 And CN 106 813 176 A .

However, such dual-function light modules have a major drawback. The bender is fixed, i.e. it remains present when the high beam function is executed. Thus, when a high beam function is used, an image of the bender is projected, creating a dark space of the shape of this bender in the projected beam. The contrast thus created in the beam is uncomfortable for the vehicle user.

In this context, there is a need to improve the homogeneity of an uncut light beam emitted by a dual-function light module.

SUMMARY OF THE INVENTION

There is provided a light module for a motor vehicle according to claim 1.

• le prisme formé comprenant une surface plane obtenue par retrait de matière de la lentille optique comprenant les dioptres ;
• la plieuse comprend des surfaces réfléchissantes ;

The light module may further include:

• the formed prism comprising a flat surface obtained by removal of material from the optical lens comprising the diopters;
• the folder includes reflective surfaces;

A projector comprising at least one light module according to the invention is also provided.

The light module according to the invention improves the homogeneity of a light beam without interruption emitted by a dual-function light module. The transition between the light emitted by the high beam function and the light emitted by the dipped beam function is continuous and smoothed. The driver is no longer disturbed by this anomaly (a less illuminated or dark area) present in the light beam emitted by the light module. Indeed, the light module corrects the drop in light intensity at the high beam/dipped beam junction when the two functions are activated. In particular, the projection lens that forms the light beam comprises a zone that modifies the trajectory of the light emitted mainly by the high beam function so that the light whose trajectory has been modified is folded back so that it is redirected towards the image of the edge of the folder in the light beam. An overlap of the light emitted by the high beam and dipped beam functions is therefore created, without a separation at the lens for the two functions being necessary. The efficiency of the light module is therefore improved thanks to a better light intensity at the range. The projection lens capable of forming the light beam with or without cut-off can therefore be a single lens and it is not necessary to have a significant modification of the lens, unlike known solutions. The area modifying the trajectory of the light is compatible with cases in which the high beam/low beam lighting is not decoupled, or only partially decoupled.

BRIEF DESCRIPTION OF THE FIGURES

• FIG. 1 illustre un exemple de faisceau lumineux à coupure projeté par un module bifonction ;
• FIG. 2 illustre un exemple de faisceau lumineux sans coupure projeté par un module bifonction ;
• FIG. 3 illustre un premier exemple d'élément optique non couvert par l'invention ;
• FIG. 4 illustre un exemple de répartition de l'éclairement sur la lentille de projection du module Bifonction crée par les rayons lumineux qui contribuent à la zone de concentration du faisceau en position de feu de croisement ;
• FIG. 5 illustre un exemple de répartition de l'éclairement sur la lentille de projection du module Bifonction crée par les rayons lumineux qui contribuent à la zone de concentration du faisceau en position de feu de route ;
• FIG. 6 illustre un exemple de l'intensité en sortie du module lumineux avant et après correction par l'élément optique du module lumineux selon l'invention ;
• FIG. 7 illustre un deuxième exemple d'élément optique non couvert par l'invention ;
• FIG. 8 illustre un troisième exemple d'élément optique non couvert par l'invention ;
• FIG. 9 illustre une vue en coupe d'un exemple de stries pouvant être disposées sur l'élément optique, non couvert par l'invention ;
• FIG. 10 illustre un quatrième exemple d'élément optique selon l'invention.

Various examples of the invention, which are not limiting in any way, will now be described with reference to the attached drawings in which:

• FIG. 1 illustrates an example of a cut-off light beam projected by a dual-function module;
• FIG. 2 illustrates an example of an uninterrupted light beam projected by a dual-function module;
• FIG. 3 illustrates a first example of an optical element not covered by the invention;
• FIG. 4 illustrates an example of the distribution of illumination on the projection lens of the Bifunction module created by the light rays which contribute to the beam concentration zone in the dipped beam position;
• FIG. 5 illustrates an example of the distribution of illumination on the projection lens of the Bifunction module created by the light rays which contribute to the beam concentration zone in the high beam position;
• FIG. 6 illustrates an example of the output intensity of the light module before and after correction by the optical element of the light module according to the invention;
• FIG. 7 illustrates a second example of an optical element not covered by the invention;
• FIG. 8 illustrates a third example of an optical element not covered by the invention;
• FIG. 9 illustrates a cross-sectional view of an example of striations that can be arranged on the optical element, not covered by the invention;
• FIG. 10 illustrates a fourth example of an optical element according to the invention.

DETAILED DESCRIPTION

A dual-function light module for a motor vehicle is proposed. The dual-function light module ensures the projection of a light beam onto a scene which is the environment of the vehicle likely to be illuminated.

The dual-function light module according to the invention can be adapted to motor vehicles that can be any type of land vehicle, for example a car, a motorcycle, or a truck. The vehicle can be equipped with one or more front headlights and/or one or more rear headlights. One or more of the front and/or rear headlights can each comprise one or more optical devices each configured to project a light beam. The dual-function light module according to the invention provides at least the following two functions.

The dual-function light module is capable of ensuring, that is to say of executing, a first function of emitting a light beam with cut-off, the cut-off delimiting a dark zone and an illuminated zone. An example of a light beam with cut-off is illustrated by the FIG. 1 . A cut-off light beam 100 comprises a "cut-off line" 101. The cut-off line is created by a folder positioned in front of one or more of the light sources of the dual-function light module such that the cut-off line of the beam is an image of the edge of the folder by the projection lens. The cut-off line marks a separation between an illuminated area 102 on the one hand and a dark area 103 on the other hand. The use of a light beam with a cut-off line makes it possible to avoid dazzling another user or the driver, for example a vehicle coming from the front. This first function without cut-off is the dipped beam function fitted to the headlights of motor vehicles.

As illustrated in the FIG. 1 , the cut-off line may extend along one or more axes, depending on the regulations. In the example of the FIG. 1 , the cut-off line extends along the two axes 101a and 101b. The orientation of these axes may be identical or different. If their orientation is identical, the two axes may be the same or parallel to each other. If, on the contrary, their orientation is different, then the cut-off line includes an angle formed by the intersection of these two axes, as illustrated in the FIG. 1 . The cut-off line is preferably horizontal on the left when the direction of traffic is on the left and forms an angle of 15° on the right with respect to the horizontal to have better visibility of the verges; conversely when the direction of traffic is on the right. Here, the horizontal axis designates an axis parallel to the horizon of the scene in a plane of the projected image. This horizontal axis can also be defined as being orthogonal to an axis perpendicular to a flat support on which the light module is arranged. Still in the example of the FIG. 1 , the cut-off line extends along the two main axes 101a and 101b of different inclinations: axis 101b is horizontal and axis 101a forms an angle with axis 101b.

The dual-function light module also provides a second function of emitting a light beam without cut-off. This beam is characterized by the fact that the dark area when emitting a cut-off light beam is illuminated when using this second function. This second function is a high beam function.
The dual-function light module according to the invention comprises two or more light sources that emit light rays, for example white light. The light sources may be filament, plasma or gas light sources. The light sources may also be sources - for example solid-state lighting sources - that comprise elements electroluminescent. An electroluminescent element may be, but is not limited to, a light-emitting diode LED, an organic light-emitting diode OLED, a polymeric light-emitting diode PLED. Thus, it is understood that any light source meeting the possible regulatory constraints of the automotive field and capable of emitting light rays can be used.

A first light source is used with the first function and a second light source is used with the second function of the dual-function light module. It is understood that this does not exclude the possibility that the first light source is used with the second function. Thus, the first light source and the second light source are used simultaneously when using the second function of emitting a light beam without cutoff of the dual-function light module; and only the first light source is used when using the first function of emitting a light beam with cutoff.

The illustrated dual-function light module also comprises one or more optical elements comprising diopters, otherwise known as dioptric elements. An element is said to be dioptric when it is composed of materials having an optical index different from that of air. The element comprises at least one transparent medium limited by diopters - for example an entry diopter and an exit diopter - which may be for example planar, convex, or concave. The term diopter designates the surfaces separating the medium of the dioptric element, for example glass, from the medium in which the lens is located, for example air. The terminology "entry diopter" designates the first diopter of a dioptric element encountered by the light rays which will pass through this dioptric element. By analogy, the "exit diopter" designates the last diopter of a dioptric element encountered by the light rays which have passed through this dioptric element. Dioptrics are, for example, prisms, lenses, glass plates and more generally any transparent element comprising dioptres. Each optical element can be characterised by a focus - when it exists - or object focus, which is the object point whose image by the optical element is at infinity. When the dual-function light module is composed of several optical elements, all of these optical elements, which can be called an optical system, are characterised by their focus, which is the object point whose image by all of the optical elements is at infinity.

The light module also comprises a folder, as known in the art. As previously mentioned, the folder is an element of the light module arranged so as to create a cut-off line when emitting a cut-off beam. The folder therefore plays a role of cover which limits the diffusion of the light emitted by the first light source in a determined zone of the scene which is the environment of the vehicle likely to be illuminated by a dipped beam function. The folder can be planar. The folder can have a more complex shape; for example, it can be formed of at least two planes in order to form the cut-off in a cut-off beam. Another example of a folder comprises two parallel planes and an inclined plane which makes the transition between the two planes. Of course, any folder can be implemented in the light module according to the invention. The folder can be arranged so that one of its edges is at the focus of the optical element or all of the optical elements. In one example, the first and second light sources are arranged on either side of the folder, such that the folder is located between the two light sources. The folder is oriented substantially parallel to the optical axis of the optical element or the optical system as the case may be. The folder may be reflective. To achieve this, it may be covered with a reflective coating, for example a reflective film, or may comprise a reflective material. Thus, the propagation of the light emitted by the first and/or second light sources is improved, which increases the light input, thereby making it possible to increase the intensity of the emitted light beam. One of the edges of the folder is arranged so as to give the required shape to the cut-off line; this edge is generally the one that is closest to the optical element of the light module. In the example of the cut-off beam presented in FIG. 1 , it is the image of the edge of the folder which defines the “cut-off line” 101 of the cut-off light beam 100. This edge of the folder which defines the cut-off line is called the cut-off edge of the folder.

In the case of a known dual-function module, the projected uncut light beam 200 comprises an image of the cut-off edge of the folder. Indeed, the folder has a non-zero thickness, as a result of which a slight hole is formed between the code zone 102, 202 and the road zone 103, 203. Thus, the folder forms a contrast between the code zone and the road zone, i.e. at the cut-off line, because the intensity of the road zone is much higher than the intensity of the code zone. The folder is typically positioned between the two light sources - the first and second light sources - and the image 201 of the cutting edge of the folder is projected as illustrated in the example of a beam without a cut-off of the FIG. 2 . Still in reference to the FIG. 2 , the area 203 of the beam which was previously dark - this dark area is noted 103 in the FIG. 1 - is now illuminated as is the illuminated area 202. The light beam 200 also includes the image of the edge of the folder 201, which breaks the homogeneity of the beam without a break.

In reference to the FIG. 6 , the solid line curve 606 illustrates the intensity of a light beam emitted by the second function as a function of the emission direction expressed in degrees. The part of the curve to the left of the ordinate axis 602 represents the code zone which has a lower intensity than the part of the curve located to the right of the ordinate axis which represents the road zone. Interestingly, it can be observed that the image of the edge of the folder in the emitted light beam produces a drop in intensity which is notably visible in the space 604 which corresponds to the cut-off line. This loss of intensity is reflected on the FIG. 6 by the fact that the curve 606, at the level of the portion 608, does not increase in a regular manner; in the space 608 to the left of the axis 602, the curve 606 does not increase. There is therefore at the level of the space 604 a contrast zone which forms, that is to say at the border between the dipped beam zone and the main beam zone. This contrast is bad for the homogeneity of the beam.

The illustrated dual-function light module comprises one or more optical elements which are capable of forming the light beam with or without cut-off and are arranged so as to correct the homogeneity of the uncut light beam emitted by the dual-function light module.

At least one optical element of the illustrated dual-function light module comprises at least one diopter which comprises one or more zones, each zone modifying the trajectory of a portion of the light, emitted by the second light source, passing through the optical element. Thus, at least one of the diopters among those of the optical elements comprises one or more zones, a zone being a delimited surface of the diopter on which the zone rests. Each of these zones modifies the trajectory of a portion of the light passing through the optical element emitted by the second light source used with the second function. The modification of the trajectory is carried out so as to deflect the rays in the direction of the image of the edge of the folder to thus restore the homogeneity of the beam without cutoff. The optical element therefore comprises one or more zones which redirect part of the light emitted by the second source, when using the function of emitting a beam without cut-off, towards zone 201, of the image of the edge of the folder. In other words, the rays coming from the second source and passing through the deflection zones are deflected downwards. It is understood that the deflection may not be perfect, and that some of these deflected rays then arrive below the cut-off, that is to say in zone 202 of the FIG. 2 . The areas are chosen so that sufficient light flux can be diverted to the image of the edge of the folder when using the second function. These areas are preferably chosen so that they have little or no effect on the light beam emitted by the first function.

The determination of the position and dimensions of a zone can be carried out using an analysis of the distribution of the luminous flux which contributes to the concentration zone (zone 204 illustrated in the FIG. 2 ) through the projection lens. More precisely, the distributions of the first luminous flux emitted by the first function and the second luminous flux emitted by the second function are used for this determination. The measurement of the distribution of a flux is carried out for the diopter on which the zone will be located. The zone, which is in fact an altered part of the diopter, will be used so as to modify the trajectory of a sufficient quantity of light so as to fill the image of the folder, corresponding to the loss of intensity, without impacting the distribution of the luminous flux emitted by the first function, that is to say without reducing the maximum intensity of the first function or without creating a defect in the homogeneity of the beam associated with the first function.

The following example details the determination of the position and dimension of a zone located on a diopter of one of the optical elements of the dual-function light module. It is understood that this example is in no way limiting, and that the dual-function light module may comprise several zones. The case where several zones are determined will be detailed later.

The first step is the measurement of the distribution of the luminous flux emitted by the first function and the measurement of the distribution emitted by the second function passing through the diopter of the optical element on which the zone will be arranged. The measurements of the respective distributions of the first and second luminous fluxes passing through the optical element of the light module are carried out using known instrumentation and techniques. The measurement can be carried out for a part of the parts of the light beams emitted by the first function and the second function; for this, a diaphragm associated with a pupil can be used. The part of the beam corresponding to the range of the beam is preferably selected: this means that the light rays of the range are selected which designate the light rays close to the cut-off line, in the axis of the road.

The range of the light module according to the invention is defined relative to an orthonormal reference frame comprising three axes X, Y, Z. This reference frame is reported for all the figures. This reference frame comprises an X axis, denoted 410, a Y axis denoted 412, and a Z axis denoted 414. The X axis corresponds to an axis parallel to the horizon and passing through the optical center of the optical element. The X axis is therefore coincident with the axis of the road, and therefore the optical axis of the module, and therefore of the projection lens. By convention, the positive direction of this axis is oriented towards the reverse gear of the vehicle. The Y axis is the axis perpendicular to the X axis and also passes through the optical center of the optical element. When we speak of horizontal, we mean a direction parallel to the horizon. The vertical is then an axis perpendicular to the horizontal. The Z axis is the axis which is perpendicular to the X and Y axes, and which is coincident with the optical axis of the optical element. The orthonormal reference frame is therefore preferably centered on the optical axis of the optical element of the light module. In another example, the orthonormal reference frame may be centered on an equivalent optical center when the module comprises a centered optical system. Generally, the Z axis coincides with the optical axis of the light module; this Z axis is also the axis with which the folder may coincide.

The light rays contributing to the range are the light rays within the beam space defined by the intervals [-5°,5°] inclusive horizontally, on the X axis, and between [-2°;2°] inclusive vertically, on the Y axis. For example, the range is delimited by box 204 on the FIG. 2 . By placing a diaphragm corresponding to this field can therefore be placed on the focal plane of the lens in such a way that only the light rays passing at the range level are preserved when measuring the distribution of the luminous flux on one of the diopters of the optical projection system. This makes it possible to carry out measurements of the two fluxes only in the part of the light beam projected by the light module for which the lack of homogeneity is the most critical, and therefore the correction made will at most only concern the range of the beam emitted by the module.

Measurements of the distribution of luminous fluxes make it possible to obtain a map of the luminous flux at the exit of the diopter or at the exit of a part of the diopter in which the fluxes are represented with isolux curves: these are closed curves (or contour lines), composed of points that have the same illuminance value on the diopter. The flux is the sum of the illuminances integrated on the surface of the diopter or on a zone of the diopter and can be noted F = ∫ E dS with F being the flux, E being the illuminance and S being the surface. It will be understood that any other representation of these measurements is possible. Similarly, it will be understood that a graphical representation of the measurements is not mandatory, that is to say that only the values of the luminous flux measurements carried out must be kept because they will be used for the second step of determining the position and dimension of a zone, described later.

THE FIG. 4 And FIG. 5 illustrate two examples of measurements of the distributions of a luminous flux at the output of a dual-function light module comprising an optical element, for example a projection lens. The FIG. 4 illustrates the distribution of the luminous flux of the beam emitted by the first function, i.e. the dipped beam function, passing through the diopter of the optical element on which the zone will be located. The FIG. 5 illustrates the distribution of the luminous flux of the beam emitted by the second function, i.e. the high beam function, across the diopter of the optical element on which the zone will be located. The measurement is carried out in these examples for the range of the beams emitted by the first function and emitted by the second function. The Z axis of the ordinates 412 and the Y axis of the abscissas 410 represent the position for which the illumination is measured. More precisely, the axis of the abscissas 410 denoted Y corresponds to an axis parallel to the horizon passing for example through the optical center of the optical element comprising the diopter on which the zone will be located, and the axis of the ordinates 412 denoted Z is the axis perpendicular to the axis 410 which can also pass through the optical center of the optical element. The axes Y and Z can in another example have as a common origin an equivalent optical center when the module comprises a centered optical system.

THE FIG. 4 And FIG. 5 therefore represent isolux curves representing different illumination values. The FIG. 4 is divided into four strips 400, 401, 402, 403. Each of these strips is of regular shape (here rectangular) and is parallel to a horizontal axis of the range of the light module, which is noted Y in the figure. The strips can all have the same dimension (lengths along the Y axis and heights along the Z axis identical), or else have different dimensions. The number of strips can vary; for information purposes, the number of strips can be between 1 and 100, inclusive. Preferably, the number of strips is between 2 and 8, inclusive. The strips do not overlap, that is, they can be placed at most one against the other.

The bands of FIG. 4 And 5 are identical, that is, they have the same dimensions and the same coordinates relative to the Y and Z axes of the reference frame.

For each band, the illuminance is summed to calculate the luminous flux passing through each band. On the FIGs. 4 And 5 , the calculated value is indicated on the right part of each of the bands 400 to 403. It appears that not all the bands have the same contribution to the emitted lighting. For example, on the FIG. 4 , the 400 band contributes little to overall illumination because the dipped beam function shown on the FIG. 4 must not emit any light above the cut-off line. On the contrary, on the FIG. 5 , the 400 band is the one with the highest luminous flux because the high beam function shown on the FIG. 5 requires that light be strongly emitted above the cut-off line. Thus, the 400 band contributes strongly to the FIG. 5 , that is to say the flux crossing the zone is high. And in contrast, the 400 band contributes weakly on the FIG. 4 , that is to say that the flow crossing the area is weak. Still with reference to the FIGs. 4 And 5 , band 403 has a contribution that is similar in both functions shown.

Thus, the band 400 can constitute an interesting zone for modifying the trajectory of a portion of the light, emitted by the second light source, passing through the optical element. A zone (or even several zones) is located on the band. All or part of the band can serve as a zone. In all cases, a zone is located on a portion of the surface of the diopter. The band 400 is an interesting zone; it offers the possibility of being able to deflect a sufficient luminous flux towards the image of the edge of the folder when using the second function, while modifying little or not at all the light beam emitted by the first function. In other words, the band 400 can comprise and be chosen as a light deflection zone because it contributes strongly to the second function (high beam) and very weakly to the first function (low beam). The division into bands of the projection of the luminous fluxes of the beams of the first function and of the second function can be carried out by relying on the distribution of the luminous flux of the light beam emitted by the second function, by identifying a region of the light beam emitted by the light module in which the luminous flux of the second function is high. Thus, in the example of the FIG. 5 , there The upper part of the map is the one that presents the most interesting characteristics as explained previously. A 400 band can therefore be defined at the level of this part of the map. It is understood that the division into bands can be carried out first of all on the distribution of the luminous flux of the first function, and then be carried over to the distribution of the luminous flux of the second function.

There are significant disparities in the distribution of luminous flux emitted by the functions of a dual-function module, as illustrated in the examples of FIGS. 4 And 5 . These disparities are exploited in the present invention to correct the inhomogeneity of the high beam light beam emitted by a dual-function light module.

After determining the distribution of the luminous fluxes of the beams of the first and second function, a second step includes the calculation of the position and dimension of the area.

As explained above, the positioning and dimensioning of the area must be carried out (i) such that an area has a second luminous flux passing through it that is sufficient when using the second function of emitting a beam without cutoff so that a portion of the light whose trajectory will be modified by the area is sufficient to fill the image of the folder in order to eliminate the homogeneity defects of the beam without cutoff, and (ii) such that an area has a first luminous flux passing through it that is low when using the first function of emitting a light beam with cutoff so that little or no light emitted by the first function has its trajectory modified by the area. For this purpose, a ratio between the measurement of the second luminous flux in the area emitted by the second function and the measurement of the first luminous flux in the same area emitted by the first function is calculated. The higher this ratio, the lower the luminous flux of the first function and the higher the luminous flux of the second function, which makes it possible to achieve the two conditions presented above. On the contrary, when this ratio decreases, the modification of the diopter in the area concerned will lead to a risk of a drop in performance for the first function with cut-off and insufficient homogeneity for the second function without cut-off.

Two non-limiting examples of methods for calculating the ratio between the second and first luminous flux are now presented.

In a first example, the ratio is calculated for all points of the light beam exiting the diopter or part of the diopter for which the distribution of the luminous flux has been measured. In this example, a graphical representation of the ratio thus calculated can be obtained; for example a map similar to that of FIG. 4 And FIG. 5 , where the curves would then represent the ratio between the luminous flux of the second function and the luminous flux of the first function. Different regions can be identified on such a map according to the values of the calculated ratio. For example, a region having a higher value of the calculated ratio than the others can be identified; the region typically has a band shape and has a ratio value that is greater than a determined value. A region therefore corresponds to an arbitrary surface of the diopter for which there is a high flux ratio, i.e. which is equal to or greater than a determined ratio value. The arbitrary surface has an area that can be defined according to an average value of the calculated ratio. The arbitrary surfaces can take the form of bands that extend parallel to the X axis 410 of the reference frame. These bands have a non-zero height along the Y axis 412 of the reference frame. Preferably, the height of a band is chosen such that the band encompasses the starting area of a peak of a calculated ratio.

In a second example, the calculation of the ratio is carried out using the bands defined on the projection of the luminous fluxes of the beams of the first function and the second function, bands illustrated on the FIGs. 4 And 5 . In both examples of the FIGs. 4 And 5 , the result of the division of each emitted beam is identical: the bands have identical coordinates in the reference frame (X, Y, Z), regardless of the function performed by the module. Thus, there is a correspondence between the divisions obtained on each of the two beams so that it is possible to create pairs of divisions, for example bands, in which each pair comprises two divisions having the same coordinates in the reference frame. For each pair of bands, a ratio between the average luminous flux of the second function in one band of the pair and the average luminous flux of the first function in the other band of the pair can be calculated.

Following the calculation of the ratio between the measurement of the distribution of the second luminous flux emitted by the second function and the measurement of the distribution of the first luminous flux emitted by the first function, a zone is selected based on this calculation. The selection of a area is now discussed. Several criteria may be used, alone or in combination, to determine which band(s) or area(s) is/are selected.

Selecting an area can include selecting the band with the highest calculated ratio, or selecting the arbitrary area with the highest ratio.

The selection of an area may comprise selecting one or more of the previously obtained bands having a high calculated ratio, or selecting one or more of the arbitrary surfaces around the regions that have a high density of points having a high luminous flux ratio. In order to discriminate between them the arbitrary bands or surfaces having the highest ratios among the calculated ratios, a predetermined threshold (i.e. a determined value) may be defined and used: only the arbitrary bands or surfaces having a ratio greater than or equal to a threshold value are selected. The threshold value may therefore be chosen arbitrarily, for example the ratio must be greater than or equal to 4.

It has been observed that good results are obtained when the zones are located at a distance greater than or equal to 10 millimeters from the center of the lens upwards - i.e. 10 mm from the horizontal axis 410. Indeed, these zones are located on a part of the diopter which is mainly used when using the second function. This distance ensures that these zones will modify the trajectory of a part of the light emitted by the second function, and will not modify the light emitted by the first function, or will only modify the trajectory of a very small part of the light emitted by the first function. In this way, said one or more zones are preferably located outside a central zone of the lens which is the zone of the lens transmitting the most light of the light beam. It is therefore preferable for the zone(s) to be sufficiently far from the center of the lens

Several zones may be present in a dual-function light module. When the optical element comprises several zones, these zones may be arranged on the same diopter or on separate diopters of the optical element. In the case where the optical element comprises several zones, the determination of the position and dimensions of each zone is done sequentially, that is to say that a new ratio is calculated at each time a zone has been added to the diopter. In this way, when several zones are located on the same diopter, the measurement of the distribution of the luminous flux is carried out at the output of the diopter so as to have a flux measurement taking into account the effects of the presence of the previously determined zones.

The optical element according to the invention is a lens which is by definition the association of two diopters. The diopters can be, but are not limited to, planar, concave, convex diopters.

The zone(s) contribute to restoring the homogeneity of the light beam emitted by the second function, i.e. when the dual-function module performs a high beam function. FIG. 6 illustrates an example of correction 600 of the intensity at the output of the light module before and after correction by the optical element of the light module according to the invention. In this figure, the ordinate axis 602 represents a measurement of the intensity at the output of the light module and the abscissa axis 603 represents the angle of the direction towards which this intensity is evaluated. The solid line curve 606 illustrates the intensity of a light beam emitted by the second function as a function of the emission direction expressed in degrees. The image of the folder in the emitted light beam produces a drop in intensity which is notably visible in the space 604 which corresponds to the cut-off line. This loss of intensity is reflected on the FIG. 6 by the fact that the curve 606, at the portion 608, does not increase. The curve 605, in dotted lines, represents the measured intensity of a new light beam by a light module according to the invention for which a correction has been applied by the optical element of the light module. The correction makes it possible to modify the beam only in the space 604, that is to say that the modified zone is located and dimensioned so that the intensity curve is smoothed to reduce the intensity "well" of the curve 606 at the space 604 which is caused by the image of the folder.

The zone(s) for altering the path of a portion of the light may include deformations of the diopter(s) at the zones. A deformation at the zone means the presence of an alteration of the diopter or deformation of the diopter. As an example of deformation, the thickness of the lens at the zone may be reduced so as to form a prism that alters the path of all light passing through it. Or, the prism may alter only a portion of the light passing through it.

Examples of areas are illustrated by the FIGs. 3 , 7 And 10 .

There FIG. 3 illustrates an example not covered by the invention, of a cross-sectional view of a plano-convex lens which comprises a first planar diopter 314 and a second convex diopter 302. This is a cross-sectional representation of the lens according to the plane (Y, Z) of the reference frame 314. The convex diopter 302 comprises a zone 306 which was obtained after having deformed the surface 304 of the diopter: the material between the zone 306 and the surface 304 was removed. As shown in the FIG. 3 , the thickness 310 of the diopter at the level of zone 306 has been reduced compared to the thickness 312 of the undeformed diopter.

The deformation at the area 304 forms a prism that modifies the trajectory of all or part of the light passing through it. The prism thus formed comprises a flat surface 306 which was obtained in this example by removing material from the lens at the area. This means that material between the edges of the area located on the diopter of the lens has been removed. It can be seen that the surface of the diopter 306 is inclined relative to the plane diopter 314 at an angle, called the inclination angle, between the area 306 and the plane diopter. The inclination of the area 306 relative to the area 304 of the convex diopter 302 is greater, thus causing a modification of the trajectory of part of the light, emitted by the second light source, passing through the optical element: the light is deflected (one can also say folded down) downwards. Preferably, as indicated by reference 308, the edges of the lens are refined, so that the diopters of the lens are parallel. The light is bent at an angle called the bending angle. The bending angle is proportional to the inclination of the place face 306 of the prism. This angle is the angle formed by the respective normals between the surface 306 and the surface 304. Thus, the deviation of the part of the light emitted by the second light source by the zone, here forming a prism, is a function of the distance of the zone from the horizontal axis passing through the optical center of the lens. On the FIG. 3 , this distance is measured on the Z axis which is perpendicular to the horizontal Y axis. The function will take negative values when the distance of the zone is positive. The distance of the zone is positive when the zone is located above the cut-off line; in practice, this is equivalent to saying that the function takes negative values when all or part of the zone is located above the horizontal Y axis. The function can be a discontinuous function, or a continuous function that can be differentiable piecewise. The modification of the trajectory of all or part of the light passing through the zone is a deviation of light. The deviation is such that the light is deflected downwards to provide additional light rays at the dark spot created by the image of the folder in the light beam, and therefore to homogenize the light beam without cutoff emitted by the second function. The area present on a diopter causes a change in the deflection angle at the output of the optical element, and therefore a modification of the trajectory compared to the case where the diopter of the optical element has not undergone any alteration or deformation. FIG. 10 illustrates an example of an optical element that can be used with the dual-function light module according to the invention, and in which a zone is located on the plane diopter 1040 of a plano-convex lens. The optical element is shown in sectional view in the plane (Y,Z) of the common reference frame 1014. Unlike the example of the FIG. 3 , the surface of the convex diopter 1020 is not altered: the surface 1070 of the plane diopter has been altered by removing material between the zone 1010 and the surface 1070. In the figure, the material removed is between the lines shown in dotted lines. Thus, and for a given point on the zone 1070 of the plane diopter 1040, the thickness 1080 of the lens has been reduced by a thickness 1090.

The zone(s) may be located on the input diopter and/or the output diopter of an optical element. Thus, on the FIG. 3 , the area and the deformation associated with the area are located on the output diopter of the optical element, while on the FIG. 10 , and according to the invention, the zone and the deformation associated with the zone are located on the entrance diopter of the optical element.

There FIG. 7 illustrates an example not covered by the invention, in which the optical element is a lens 700 which has zero or substantially zero optical power; in this example the optical element is a plate. In theory, only an ideal plate has zero optical power. The FIG. 7 illustrates a cross-sectional view of the optical element in the plane (Y,Z) of the common reference frame 714. The exit diopter of this optical element has a zone 702. The diopter before alteration is indicated by the reference 710 and the material removed is shown in dotted lines. The zone 702 forms a prism with the entrance diopter 712. The edge 706 of the plate close to the prism has a thickness less than the opposite edge of the plate 708. As illustrated by the FIG. 7 , a portion of the light rays 704 are deflected. It is understood that, when one or more zones are included on the diopter of a lens of zero optical power, the lens of zero power is associated with one or more lenses with non-zero powers forming the light beam emitted by the light module. In this case, the lens of zero power can be placed before the other lens(es): the principle of adding optical effects therefore makes it possible to obtain, when using the second function, a homogeneous light beam.

There FIG. 8 illustrates an example not covered by the invention of an optical element which is a lens 800 of substantially zero optical power, as in the example of the FIG. 7 . The lens is represented in the common reference frame 814. This lens 804 is a blade and comprises a zone 802 which modifies the trajectory of a portion of the light passing through the optical element. Streaks are arranged on an upper part 803 of the optical element which encompasses the zone 802: the upper part 803 extends on either side of the zone 802 along the X axis of the reference frame. The zone 802 is free of streaks. The streaks are an optical structure whose function is to homogenize the light beam by creating a blur: the streaks locally deflect the incident light rays. The FIG. 9 illustrates the cross-sectional view of these striations in the plane (Y,Z), in the common reference frame 814, which are semi-circular structures 901, with a width 903 varying between 0.5 mm and 2 mm, limits included, and which are not covered by the invention. These are shallow grooves, which may be lines, rectilinear or curved, varying the thickness 905 along the z axis of the reference frame 814. Still in the example of the FIG. 8 , the portion 805 of the blade located under the zone 802 and the portion 804 of the blade located under the grooved upper part are devoid of grooves in order to prevent the grooves from altering the cut-off line: in fact, the zone 802 and the parts of the diopter 804 and 805 are crossed by rays participating in the range of the first function of emitting a cut-off beam. The portion 805 defines the central zone mentioned above.

The light module according to the invention can be used within a vehicle. Thus, a headlight can comprise one or more light modules, each of the light modules being a dual-function module. The light modules can be identical, or different according to the examples described.

Claims (4)

1. Luminous motor-vehicle module capable of being configured to execute a first function emitting a cutoff-containing light beam (100), the cutoff delineating an illuminated region (102) and a dark region (103), and a second function emitting a cutoff-free light beam (200), the dark region (203) then being illuminated, comprising:

   - a first light source capable of being used with the first function and a second light source capable of being used with the second function, the first function being a low-beam function and the second function being a high-beam function;

   - a deflector arranged to create the cutoff of the cutoff-containing light beam when the first function is executed;

   - a planar-convex projecting lens comprising an optical centre, a planar entrance dioptric interface (1040) and a convex exit dioptric interface (1020), which are capable of forming the light beam with or without cutoff, the planar entrance dioptric interface (1040) comprising a region (1070) that modifies the path of one portion of the light, emitted by the second light source, passing through the lens, so as to redirect one portion of the light emitted by the second source during emission of the cutoff-free light beam toward an image of the edge of the deflector, characterized in that the region is a deformation of the entrance dioptric interface of the lens, the deformation corresponding to a reduction in the thickness of the lens in the region (1070) so as to form a prism that modifies the path of all or some of the light that passes through it,

   the region being located at a distance greater than or equal to 10 mm from the horizontal axis passing through the optical centre of the lens upwards when the luminous module is placed in the vehicle, in a portion of the dioptric interface that is mainly employed during use of the second function.
2. Luminous module according to Claim 1, wherein the prism formed comprises a planar surface obtained by removing material from the optical lens comprising the dioptric interfaces.
3. Luminous module according to one of Claims 1 to 2, wherein the deflector comprises reflective surfaces.
4. Headlamp comprising at least one luminous module according to one of the preceding claims.

Images